The Fairfax County Board of Supervisors yesterday said $2.6 million in bonds to build the Reston Community Center after being warned of the consequences of additional bond sales for small districts in the county.

Walter Craigie, the county's bond counsel, said Fairfax County could jeopardize its triple. A bond rating by continuing to incur "underlying debts" for new taxking districts.

But board chairman John F. Herrity said he believes the board has taken a conservative policy toward approving any future small districts "in view of its potential impact on our credit." He said he doesn't know of any plans to approve any new taxing districts.

Taree toher special districts created by the county have bond indebtedness. They are McLean, Pimmit Hills, and the Greenbriar-Chantilly districts.

Fairfax said the $2.6 million worth of general obligation bonds at a net interest of 4.983575 per cent - "an excellent bid," according to Craigie.

Craigie said the bid, which is below the current long-term interest rate of 5.56 per cent, would save the tax payers of Small District 5 in Centreville and Dranesville Districts an estimated $173,420 in interest payments over the 20-year life of the bonds.

The county received three bids for its bonds. The winning bid was submitted by the Northern Trust Company of Chicago.

Craigie said he was disappointed in the showing; he had hoped the county would receive at least six bids.

He attributed the few bids to the two different ratings assigned to the bonds.

Moody's Investors' Service gave the bond sale a double-A rating, while Standard and Poor's rated it A-minus.

Craigie sadi the "hybrid" rating was mostly because Standard and Poor's said the Reston district "lacked seasoning and maturity." He said the district, which was created in 1975, has no specific tax collections nor a history of tax receipts and disbursements.

He said Moody's Investor Service was impressed with the socio-economic conditions of the county.

The $2.6 million bond issue was approved by a majority of the voters in the special district in June, 1975.

The center will be located in the Hunters Woods Village Center.It will include a 274-seat auditorium, a 25-meter indoor swimming pool, multipurpose meeting rooms, a game room, kitchen and dining area, and office space.